The present invention relates to a lock mechanism for preventing rotation of a spindle on which a plurality of magnetic disks are coaxially provided.
A magnetic disk drive has a plurality of magnetic disks coaxially provided on a spindle which is rotated by a spindle motor. The magnetic disk drive also has a head carriage for driving a plurality of magnetic heads, each of which is provided for carrying out read and write operations to a respective surface of the magnetic disks, in a radial direction of the magnetic disks. The magnetic disks, spindle, head carriage, and magnetic heads are generally in a sealed enclosure to form a head-disk assembly.
In the read and write operations, the magnetic disks are rotated together with the spindle causing each of the magnetic heads to fly on the respective surface of the magnetic disks with a fine clearance owing to the air bearing effect. On the other hand, the magnetic heads are in contact with the respective disk surfaces when the magnetic disks are not rotated, i.e., while the disk drive is not operated or while the disk drive is shipped. It is preferable to prevent the rotation of the spindle to reduce the occurrence of damage to the magnetic heads and disk surfaces, when the magnetic disks are not rotated.
To this end, a conventional lock mechanism for preventing rotation of a spindle is disclosed in U.S. Pat. No. 4,331,989, which issued to Viskochil on May 25, 1982. The conventional lock mechanism includes a lock arm one end of which is provided with a brake pad for engagement with the spindle. The lock arm is connected to a lever which is manually operated to first and second positions for locking and unlocking the rotation of the spindle, respectively.
The locking operation should be carried out after the rotation of the magnetic disk completely stops because the magnetic head tends to clash with the disk surface if the rotational speed of the disk is suddenly decreased. The conventional lock mechanism has a disadvantage in that an operator must confirm the complete stop of the rotation of the disk before the locking operation.
The Viskochil patent also suggests an electrically operable lock mechanism including a linear solenoid; however, no arrangement for energizing the lock mechanism after the complete stop of the disk rotation is disclosed or suggested in the Viskochil patent.